Pallet-end-stone cap for watch-movements.



W. B. MEHL.

PALLET END STONE GAP FOR WATCH MOVEMENTS. APPLICATION FILED JULY 17, 1909.

Patented Jan. 17, 1911.

UNITED STATES PATENT OFFICE.

WALTER B. MEHL, or wAL'rHAi/r, MASSACHUSETTS, ASSIGNOR, nY MESNE ASSIGN- MENTS, T0 THEIKEYSTONE WATCH CASE COMPANY, or PHILADELPHIA, PENN- SYLVANIA, A CORPORATION OF PENNSYLVANIA.

PALLET-END-STONE CAP FOR WATCH-MOVEMENTS.

Specification of Letters Patent.

Patented Jan. 17, 1911.

Application filed July 17, 1909. Serial No. 508,111.

Movements, of which the following is a specification.

My invention relates to an improvement in watch movements, and more particularly to the construction and arrangement of means for retaining the pallet end-stone cap in its proper position. The retention of this member in a watch movement, hasheretofore caused much trouble to the manufacturer and repairer, in that the part is so small that great difiiculty has been experienced in properly securing it in place. In the construction of a watch movement, this member has heretofore been made semi circular in form and secured to the pallet bridge by means of one short screw about.

fifteen one-thousandths of an inch in length, and containing approximately two hun red and fifty threads to the inch. It will therefore be understood that the slightest undue.

strain placed upon the screw in turning the same home, will strip the thread, thereby rendering it useless, and in many instances necessitating the re-tapping-of the threaded openin in the'pallet'bridge to which it is secure and in some instances necessitating a special larger screw, and in other in stances, the renewal of the entire pallet bridge. Even when the parts are accurately made and fitted, this minute screw is insufficient to always hold the cap in place, and any slight lateral pressure thereon will necessarily disturb the relation between the several parts. In my improved'movement, Iv

have overcome this difficulty by forming this cap in somewhat the formor shape of a keystone to be retained in a recess formed in the pallet bridge, havinginclined sides to corres 0nd with the inclined sides of the cap, an providing sufficient stock in the-bridge to receive and retain two screws of considerably greater length than the one hereto- 7 fore used.

In the accompanying drawings, Figure 1 is a plan viewof a part of'a watch move- Fig. 2 is a detached plan view showing the means for retaining the pallet end-stonecap in its proper position on the pallet bridgei Fig. 3 is 'a sectional view taken on the line 33 of Fig. 2, a pallet fork being also shown in section.

Referring to the drawings, it will be seen that the pallet bridgeS issecured to the dial plate 6 by meansofthehvo screws 12,

the upper surface of the brid e being 1 away to receive the cap 13, the atter having the outline,} as clearly illustrated in Figs.

- 1 and 2, that is, with the inclined edges 14 to fit against similarly inclinededges of the recess in the bridge, whereby to provide against any lateral -movement of the cap.

cut

The under side of this bridge is also cut away, as illustrated at 15, (Fi 3), the stock or metal of which the bri ge is formed, being carried downwardly into this recess to form the lugs 16, and tapped to receive the retaining screws 17, said lugs 16 permitting of the use of screws of much reater length than has formerly been possib e. It will be understood, of course, that this recess 15 in the under side of the bridge is absolutely essential to accommodate the pallet fork 15, and hence the thickening of the metal of this part of the bridge is impossible, the consequence being that heretofore a sin le minute screw has been utilized for holding the pallet end-stone cap 13 in its position on the bridge. Asbefore stated, the length of the screw heretofore used has been approximately but Yfifteen one-thousandths of an inch, and contains about two hundred and fifty. threads to the inch. It will therefore be readily understood that any undue strain placed upon this minute screw will necessaril strlp it of its'threads', and permit of the isplacement or movement of the'ca on the brid e. By shaping the cap asv a ove describ .that IS, giving it approximatelly the form of a keystone to fit in a correspon ingl shaped recess in the bridge, and

the ening the metal On the sides of therecess to form-the lugs 16, to permit of the use'of twocomparatively longer screws, the

objections to the former construction of brid all ment '0 viated. a

From the foregoing it will be understood e and cap have been overcome, and anger of the displacement or movethe cap on the pallet bridge, 0b-

that my invention is exceedingly simple, and, as has been shown in practice, the 1111- proved means of securing the pallet endstone cap in place, permits of the easy andready location of said cap, and'operate as a positive lock against accidental movement of the several parts; furthermore, these means tend to prevent danger of stripping the threads on the small retaining screws and bridge, and also relieve the screws of a large part of the strain iin osed upon them.

Having fully describe my invention, what I claim as new and desire to secure by Letters Patent, is

1. In a watch movement, the combination with a dial plate,-0f a pallet bridge secured thereto and formed with a recess having inclined sides, a pallet end-stone cap having inclined sides fitting in said recess in said pallet bridge, and screws for securing said bridge and cap in their roper relative positions, substantially as escribed.

2. In a watch movement the combination with a dial plate, of a pallet bridge secured thereto, and provided with a recess having inclined sides, a pallet end-stone cap having inclined sides and fitting in said recess in said pallet bridge, and screws passing through said cap and into said bridge for holding the parts in their proper relative positions, substantially as described.

3. In a watch movement, the combination with a dial plate, of a pallet brid e secured, 

